1. Technical Field
The present invention relates to a conducting network composite for storing gas such as hydrogen, carbon dioxide, or the like, and a method for preparing the same.
2. Description of the Related Art
Recently, a renewable energy source such as hydrogen has been in the social spotlight. Particularly, hydrogen has higher chemical energy density (142 MJ/kg) than that of other hydrocarbon fuel. Therefore, it is known that hydrogen may play an important role in solving problems associated with energy shortage. In detail, U.S. Department of Energy determines various reference values for reversible gravimetric and volumetric values of hydrogen storage in applying hydrogen to a transportation field. For this reason, research into various materials for storing hydrogen has been conducted.
Conducting polymers having various nanostructures have properties as an organic conductor, and a low volume system, and interesting physiochemical properties and are significantly useful for various purposes. Due to development of the conducting polymer, an interest in optical, electronic, and electric properties required in various application fields has increased. Due to unique properties of the conducting polymers used in various industrial fields, researches into synthesis and characterization of nanostructures based on these conducting polymers has been actively conducted. Among the conducting polymers, research into polyaniline (PANI), polypyrrole (PPY), and polythiophene has been mainly conducted. Particularly, since polyaniline and polypyrrole have excellent thermal and electrical properties and environmental stability, various researches has focused on synthesis of a polyaniline-polypyrrole copolymer (F. Fusalba, D. Belanger, J. Phys. Chem. B. 1999, 103, 9044.; J. Stejskal, M. Trchova I. A. Ananieva, J. Janca, J. Prokes, S. Fedorova, I. Sapurina, Synth. Met., 2004, 146, 29.; P. Xu, X. Han, C. Wang, B. Zhang, X. Wang, H. L. Wang, Macromol. Rapid Commun. 2008, 29, 1392).
A conducting PANI-PPY composite has a combination of excellent properties as compared to properties of each of the polymers themselves. The reason is that the conducting PANI-PPY composite has unique conducting nanostructure nanofiber morphology. Particularly, a one-dimensional structure of polyaniline nanofiber has an advantage in that the one-dimensional structure of polyaniline nanofiber may be easily produced while adjusting a diameter thereof. In addition, polyaniline has excellent oxidation-reduction properties for reducing predetermined metal ions, and a PANI-metal nanoparticles composite applicable to various application fields may be prepared due to these properties (J. Huang, R. B. Kaner, Angew. Chem. Int. Ed. 2004, 43, 5817.; D. Li, R. B. Kaner, J. Am. Chem. Soc. 2006, 128, 968.; N. R. Chiou, A. J. Epstein, Adv. Mater. 2005, 17, 1679).
In the related art, research into a technology for using a conducting polymer as hydrogen storage material has been reported. In this research, it was reported that commercial PANI and PPY may store at most 8 weight % of H2 (S. J. Cho, K. S. Song, J. W. Kim, T. H. Kim, K. Choo, Fuel chem. Div. Prepr. 2002, 47, 790). Although other researchers did not succeed in reproducing the result as described above (B. Panella, L. Kossykh, U. Dettlaff-Weglikowsa, M. Hirscher, G. Zerbi, S. Roth, Synth. Met. 2005, 151, 208), the conducting polymer and a nanocomposite thereof has been spotlighted as an attractive material for storing hydrogen (S. J. Cho, K. Choo, D. P. Kim, J. W. Kim, Catal. Today 2007, 120, 336.; J. Germain, J. M. J. Frechet, F. Svec, J. Mater. Chem. 2007, 17, 4989.; M. U. Jurczyk, A. Kumar, S. S. Srinivasan, E. K. Stefanakos, Int. J. Hydrogen Energy 2007, 32, 1010.; N. B. McKeown, P. M. Budd, D. Book, Macromol. Rapid Commun. 2007, 28, 995.; S. S. Srinivasan, R. Ratnadurai, M. U. Niemann, A. R. Phani, D. Y. Goswami, E. K. Stefanakos, Int. J. Hydrogen Energy 2010, 35, 225.; D. E. Demirocak, S. Kuravi, M. K. Ram, C. K. Jotshi, S. Srinivasan, A. Kumar, Y. Goswami, E. Stefanakos, Adv. Mater. Research 2012, 445, 571).
However, since the morphology, chemical formula, and composition of a composite material have a significant influence on a hydrogen storage property, it is not easy to prepare a composite material having excellent physical and chemical properties.